Previous studies have shown that micrococcal nuclease selectively excises genes which are in the transcriptionally active conformation in chromatin. The selectivity of this digestion process permits the fractionation of chromatin into transcriptionally active and inactive regions. In the proposed studies we will first use micrococcal nuclease as a probe for the alpha-fetoprotein gene in chromatin to determine if the loss of alpha-fetoprotein mRNA during normal liver development and the reappearance of alpha-fetoprotein mRNA during liver cancer are accompanied by corresponding alterations in the configuration of the alpha-fetoprotein gene in chromatin. Since chromosomal proteins are presumably responsible for the ordering of the DNA into template active regions, we will characterize these proteins associated with transcribed DNA in normal and malignant hepatocytes. In addition, chromatin reconstitution experiments will be employed to define the class of chromosomal proteins responsible for the generation of the alpha-fetoprotein genes into transcriptionally active conformations during normal and malignant development. These studies should therefore further our understanding of the transcriptional organization of chromatin during normal development and neoplastic transformation.